|
|
Activation of collimating system of linear accelerator through photon radiation and its impact on the doses received by the staff.
KUBÍKOVÁ, Adéla
The diploma thesis on the topic "Activation of Collimating System of Linear Accelerator through Photon Radiation and its Impact on the Doses Received by the Staff" is divided into two parts, a theoretical and a practical part. The introductory theoretical part is devoted to the basic information about ionizing radiation. What are the types of ionizing radiation, its characteristics, properties and sources of ionizing radiation. Furthermore, there are mentioned direct and indirect interactions of ionizing radiation, a brief description of charged particle accelerators, collimator systems and radioisotope irradiation devices. Another part deals with radiation protection, basic legislation, methods and principles of radiation protection, personal dosimetry and medical supervision of radiation workers. Literary sources, available internet links and valid legal regulations were used for the work. In the practical part, a number of measurements were carried out to measure and to analyse the doses of secondary radiation of the linear accelerator collimator system for different photon beam energies, depending on time, distance from source, position of radiologic assistant around the table when working with the patient, as well as sizes of irradiated field. The aim of the work was to find out how large the doses of secondary radiation are, although measurable, but their values are not sufficient to be detected by personal dosimeters of radiological assistants. Confirm the hypothesis that the doses from the secondary radiation of the linear accelerator collimator system are so low that the dose power does not exceed 0.031 mGy/hr. The results obtained from various measurements are processed into transparent tables and graphically displayed. Based on the results of the measurements, the hypotheses were confirmed.
|
|
|
Radiation exposure of persons working in the risk of ioniing radiation in the University Hospital in Pilsen
ULČOVÁ, Radka
The diploma thesis on "Radiation exposure of persons working at risk of ionising radiation at the Pilsen University Hospital" is divided into two parts. The first analyses personal effective doses of the employees of the Pilsen University Hospital in 20092013, and the second focuses on measurements of secondary radiation created after the activation of collimator systems of linear accelerators. The introduction of the theoretical part discusses the history of radiology, followed by a summary of information on the sources of ionising radiation, its characteristics, properties, methods of interaction with the environment and biological effects on organisms. The chapter on radiation protection focuses on basic legislative regulations relevant to the topic. In the Czech Republic, radiation protection of people working with sources of ionising radiation is mostly based on Act No. 18/1997 Coll., on peaceful uses of nuclear energy, and Regulation of the State Office for Nuclear Safety No. 307/2002 Coll., on radiation protection. The thesis also lists dose limits and basic information about personal dosimetry, and the theoretical section is concluded with information on the methods of protecting personnel and on provided healthcare. The thesis uses as its sources primary literature, internet links, current legislation and data from the database of the State Office for Nuclear Safety on records from personal dosimeters in the analysed period. The thesis had two objectives. The first was to compare levels of exposure at the Pilsen University Hospital. The analysis involved 579 persons in total; after arranging the data into tables and dividing employees into groups by the type of tasks they perform and their job, it was possible to compare median value indicators, confirming the hypothesis that persons carrying out intervention tasks are exposed to more ionising radiation. In order to compare the development of doses over time, a double-selection t-test was performed on data from 2009 and 2013, confirming the effectiveness of anti-radiation measures adopted at the University Hospital and a reduction in the exposure of employees in this period. The second objective was to confirm or deny the hypothesis that secondary radiation created by collimator systems, while measurable, is not sufficiently large to be detected by personal dosimeters. In order to achieve this objective, measurements were carried out at the Oncology and Radiology Clinic of the Pilsen University Hospital. The first measurements tried to determine the relationship between dose and time at various levels of energy, the second compared the relationship between dose and distance from the collimator plane and the third monitored the number of exposures until the collimator plates are saturated and dose is no longer increased. All results were arranged in tables and projected in charts. The results of the research confirmed the hypothesis that secondary radiation created during the use of high-energy equipment is just below the detection limits of personal dosimeters. For this reason, it is recommended to frequently rotate personnel working with the equipment.
|
guest ::
